Mercury contamination in the Yatsushiro Sea, south-western Japan: spatial variations of mercury in sediment

Mercury-contaminated effluent was discharged into Minamata Bay from a chemical plant over a 20-year period until 1965 (from 1958 to 1959, effluent was discharged into Minamata River), causing Minamata disease. In an effort to characterize the extent of the contamination in the Yatsushiro Sea, the vertical and horizontal distributions of mercury in sediment were investigated. Sediment was sampled at 62 locations in the southern part of the sea from 4 to 6 March 1996. In the lower layers of the long cores of sediment, the total amount of mercury was at a relatively uniform low concentration. We interpret these low values to represent the background concentration absent of anthropogenic influence. The background value thus estimated for the Yatsushiro Sea was 0.059 +/- 0.013 mg kg(-1) (mean +/- S.D., n = 51). The highest concentration in each sample ranged from 0.086 to 3.46 mg kg(-1) (mean, 0.57 mg kg(-1)). The higher values were obtained at stations near Minamata Bay and the Minamata River (the sources of the pollution). Concentrations decreased with distance from the source. An inspection of the vertical profiles of mercury concentration in cores suggested that the deposited mercury had not been fixed in sediment but had been transported, despite 30 years having past since the last discharge of contaminated effluent. At nine stations, extractable inorganic and organic mercury concentrations were determined differentially. Inorganic mercury is the predominant species in sediment and organic mercury comprising approximately 1% of the total.     

A preliminary study on mercury contamination to the environment from artisanal zinc smelting using indigenous methods in Hezhang County, Guizhou, China: Part 2. Mercury contaminations to soil and crop

Artisanal zinc smelting using indigenous method in Hezhang County, Guizhou, China has posed seriously environmental pollution to the local environment. Within less than 150 km2 area in Hezhang, a few metric tons of mercury were released into the atmosphere each year since 1989 due to artisanal zinc smelting, and the surface waters were seriously contaminated with mercury. For the first time, we investigated the mercury contamination to the local soil and crop compartments due to mercury emissions from artisanal zinc smelting activities in this area. Mercury distribution patterns in 5 soil profiles collected in artisanal zinc smelting area showed that the top soils were seriously contaminated with mercury. The soils from agriculture land close to the zinc smelting areas were also contaminated with mercury due to the deposition of mercury species that emitted from artisanal zinc smelting processes. Total mercury concentrations in top soils decrease exponentially with distance from the zinc smelting area. Corn plants that were cultivated in agriculture land close to the zinc smelting area were also contaminated with mercury. Mercury concentration in corn plant tissue increased in the order of grains相似文献   

Tests of the fidelity of lake sediment core records of mercury deposition to known histories of mercury contamination

There has been recent controversy over the discrimination between natural and anthropogenic loadings of mercury to lakes. Sediment core profiles have been interpreted as evidence that inputs to lakes have increased. Some investigators have argued, however, that mercury may be sufficiently mobile in sediments to generate profiles that are misinterpreted as historical records. This argument can be tested where the histories of inputs of mercury are known independently from other kinds of information. We have such cases in Canadian lakes and we have been able to assemble sediment core records for comparison with known source histories. Three cases are represented by Clay Lake in Ontario where the source was a chlor-alkali plant with a known history of mercury discharges, Giauque Lake in the Northwest Territories where mercury was used at a gold mine to extract gold from ore, and Stuart Lake in British Columbia where a mercury mine operated for a known period at Pinchi Lake, the lake immediately upstream from Stuart Lake. In these cases lake sediment cores were dated using lead-210 and cesium-137 and then slices were analysed for mercury. The histories of mercury deposition derived from the cores agreed well with the known histories of inputs.     

Environmental assessment of mercury contamination from the Rwamagasa artisanal gold mining centre, Geita District, Tanzania

This study presents the results of an environmental assessment of mercury (Hg) contamination in the Rwamagasa artisanal gold mining area, northwest Tanzania, and the potential downstream dispersion along the River Malagarasi to Lake Tanganyika. At the time of sampling, generally low concentrations of Hg (<0.05 mg/kg) occurred in most cultivated soils although higher Hg (0.05-9.2 mg/kg) was recorded in urban soils and vegetable plot soils where these are impacted by Hg-contaminated water and sediment derived from mineral processing activities. Hg in vegetable and grain samples is mostly below the detection limit of 0.004 mg/kg Hg, apart from 0.007 and 0.092 mg/kg Hg in two yam samples and 0.011 to 0.013 mg/kg Hg in three rice samples. The standardized (i.e., standardized to 10 cm length) Hg concentrations in Clarias spp. increase from about 0.01 mg Hg/kg for the River Malagarasi delta to 0.07, 0.2, and 1.6 mg/kg, respectively, for the Rwamagasa 'background', moderately and most contaminated sites. For piscivorous (Lates, Brycinus, and Hydrocynus spp.), insectivorous (Barbus spp.), and planktivorous (Haplochromis spp.) fish species, the 10-cm standardized Hg concentrations increase from about 0.006 mg/kg for the River Malagarasi-Lake Tanganyika area to 0.5 and 3.5 mg/kg, respectively, for the Rwamagasa moderately and most contaminated sites. The low concentrations of Hg in fish from the Malagarasi River delta and Lake Tanganyika indicate that Hg contamination from the Rwamagasa area does not have a readily discernible impact on the biota of Lake Tanganyika. Many of the fish samples from Rwamagasa exceed guidelines for human consumption (0.5 mg/kg) as well as the WHO recommended limit for vulnerable groups (0.2 mg/kg). Tissue total Hg (THg) of all fish collected from the River Malagarasi-Lake Tanganyika subarea is well below these guidelines. Potential human exposure through consumption of 300 g/day of rice grown on Hg-contaminated soils is 5.5 microg/week. Consumption of 250 g Nile perch (Lates spp.), 500 g tilapia (Oreochromis spp.), and 250 g of catfish (Clarias spp.) each week would result in an intake of 65 microg Hg/week for people consuming only fish from the Mara and Mwanza regions of Lake Victoria and 116 microg Hg/week for people in the Rwamagasa area consuming tilapia and Nile perch from Lake Victoria and catfish from mining-impacted streams. This is lower than the Provisional Tolerable Weekly Intake (PTWI) of 300 microg for Hg in the diet set by the WHO and the FAO. Inadvertent ingestion of soil containing 9 mg Hg/kg at a rate of 80 mg/day would give an additional estimated weekly intake of 5 microg THg, whereas the persistent and purposeful consumption of soil (geophagia) at a rate of 26 g soil/day would produce an additional chemical exposure of 230 microg Hg/day.     

Historic brownfields and industrial activity in Kingston, Ontario: Assessing potential contributions to mercury contamination in sediment of the Cataraqui River

The waterfront of historic Kingston, Ontario (pop: 113,000) has been used for industrial activities for over a century. More than 40 industries have existed within the inner harbour, and while many of these industries are no longer present, the properties that they operated on remain as potential sources of persistent contamination to the present day, including mercury. To assess the extent and distribution of total mercury (THg) contamination, 21 sediment cores as well as pore water samples were collected within the inner harbour of Kingston. The spatial distribution of THg in the surface sediment is not homogenous; with concentrations in the surface sediment along the southwestern shoreline, adjacent to the former industrial properties, are significantly greater (p < 0.01) than the rest of the inner harbour, and were above the Federal severe effect limit (> 2000 ug/kg;) guideline for sediment. MeHg was detected in some sediment cores, and was found to have a significant, positive correlation with [THg] in the surface sediment (0-5 cm). THg was not found in storm sewer discharges, but was detected in terrestrial soil near the Kingston Rowing Club at a concentration of more than 4000 ug/kg. Significant [THg] was detected in runoff draining from contaminated shoreline soils, indicating that erosion from terrestrial sources may be an ongoing source of Hg to the sediment. It can be concluded that there is an increased risk over time to surrounding ecosystems where properties with historical contamination are not remediated until they are developed.     

胶州市城区河道水环境综合整治初探

衣文通过对胶州市城区河道水环境现状问题的分析研究．提出城区河道水环境综合整治的原则与措施,以期得到城区河道综合整治的有效经验．     

Contamination by chlorinated hydrocarbons (DDT,PCBs) in surface sediment and macrobenthos of the river Adige (Italy)

Surface sediments and macrobenthos communities have been employed as contamination indicators for halogenated hydrocarbons (DDT and PCBs) in the river Adige and its tributaries Fibbio and Alpone in the province of Verona. Two sampling campaigns were carried out, before and after the spring-summer floods, to determine the effects of this event on the contamination of the river. The halocarbons in the sediment were found to be associated with the fine fraction (< 53 μm) and organic carbon. From the relative concentrations of contaminants determined at various sampling stations, some information has been obtained on the sources.     

A comparison of the non-essential elements cadmium, mercury, and lead found in fish and sediment from Alaska and California

Concentrations of three non-essential elements (cadmium (Cd), mercury (Hg), and lead (Pb)) were determined in sediment and fish from several locations in Alaska (AK) and California (CA) and used to examine differences in bioaccumulation within and between geographic locations. We analyzed tissue (liver, muscle, gill, and stomach contents) from white croaker (Genyonemus lineatus) and English sole (Pleuronectes vetulus) in California and flathead sole (Hippoglossoides elassodon) in Alaska, in addition to several species of invertebrates (mercury only). As found in previous work on arsenic (As) [Meador et al., 2004], Cd in fish liver exhibited a negative correlation with sediment concentrations. No such correlations were found for Hg and Pb when fish liver and sediment were compared; however, these metals did exhibit a positive relationship between liver and organic carbon normalized sediment concentrations, but only for the CA sites. Sediment concentrations of Hg at the AK sites were lower than those for the CA sites; however, AK invertebrates generally bioaccumulated more Hg than CA invertebrates. Conversely, Hg bioaccumulation was higher in CA fish. Even though ratios of total metal/acid volatile sulfides (AVS) in sediment were one to two orders of magnitude higher for the AK sites, bioaccumulation of these elements was much higher in fish from the CA sites. Bioaccumulation factors ([liver]/[sediment]) (BAFs) were highest at relatively clean sites (Bodega Bay and Monterey), indicating that elements were more bioavailable at these sites than from more contaminated locations. The observation of high BAFs for As in fish from Alaska and low BAFs for the California fish, but reversed for Cd, Hg, and Pb in this study, implies that differences in fish species are less important than the unique geochemical features at each site that control bioavailability and bioaccumulation and the potential sources for each element. Additionally, these data were also used to examine the metal depletion hypothesis, which describes the inverse relationship between elements and organic contaminants documented in some monitoring studies. Our results suggest that the enhanced bioavailability of the metals at some uncontaminated sites is the main determinant for the inverse correlation between metal and organic contaminants in tissue.     

Spatial variations of mercury in sediment of Minamata Bay, Japan

Mercury-contaminated effluent was discharged into Minamata Bay from a chemical plant over a period of approximately 40 years until 1968. In October 1977, the Minamata Bay Pollution Prevention Project was initiated to dispose of sedimentary sludge containing mercury concentrations higher than 25 mg kg(-1). In March 1990, the project was completed. In an effort to estimate current contamination in the bay, the vertical and horizontal distributions of mercury in sediment were investigated. Sediment core samples were collected on June 26, 2002 at 16 locations in Minamata Bay and Fukuro Bay located in the southern part of Minamata Bay. The sediment in Fukuro Bay had not been dredged. The total mercury concentration in surface sediment was 1.4-4.3 mg kg(-1) (2.9+/-0.9 mg kg(-1), n=9) for the dredged area of Minamata Bay and 0.3-4.8 mg kg(-1) (3.6+/-1.6 mg kg(-1), n=4) for Fukuro Bay. In the lower layers of long cores taken from both areas, the total mercury concentration decreased with depth and finally showed relatively uniform low values. These values can be considered to represent the background concentration absent of anthropogenic influence, which was estimated for the study area to be 0.068+/-0.012 mg kg(-1) (n=10). From the surface, the total mercury concentration in Fukuro Bay increased with depth and reached a maximum at 8-14 cm. In Minamata Bay, several centimeters from the surface the total mercury concentration did not change significantly having considerably higher values than the background level. At six stations, the methylmercury concentration was determined. Although the vertical variations were similar to those for total mercury, Fukuro Bay sediment showed a higher concentration of methylmercury than Minamata Bay sediment.     

长江南通区段及内河淤泥塑性指数试验研究

通过对长江南通区段及内河淤泥塑性指数试验,得出了该地区不同河道淤泥塑性指数分布情况,对淤泥烧结砖的淤泥原料要求进行探讨.研究结果表明,长江南通区段及主要河道淤泥塑性指数均大于7,集中在11左右,可以取代传统烧结砖使用的黏土材料.研究成果可为南通境内淤泥制品企业的原料选择与使用提供理论依据,并为行业内部的整并与管理提供参考.     

Critical review of mercury fates and contamination in the arctic tundra ecosystem

Mercury (Hg) contamination in tundra region has raised substantial concerns, especially since the first report of atmospheric mercury depletion events (AMDEs) in the Polar Regions. During the past decade, steady progress has been made in the research of Hg cycling in the Polar Regions. This has generated a unique opportunity to survey the whole Arctic in respect to Hg issue and to find out new discoveries. However, there are still considerable knowledge gaps and debates on the fate of Hg in the Arctic and Antarctica, especially regarding the importance and significance of AMDEs vs. net Hg loadings and other processes that burden Hg in the Arctic. Some studies argued that climate warming since the last century has exerted profound effects on the limnology of High Arctic lakes, including substantial increases in autochthonous primary productivity which increased in sedimentary Hg, whereas some others pointed out the importance of the formation and postdeposition crystallographic history of the snow and ice crystals in determining the fate and concentration of mercury in the cryosphere in addition to AMDEs. Is mercury re-emitted back to the atmosphere after AMDEs? Is Hg methylation effective in the Arctic tundra? Where the sources of MeHg are? What is its fate? Is this stimulated by human made? This paper presents a critical review about the fate of Hg in the Arctic tundra, such as pathways and process of Hg delivery into the Arctic ecosystem; Hg concentrations in freshwater and marine ecosystems; Hg concentrations in terrestrial biota; trophic transfer of Hg and bioaccumulation of Hg through food chain. This critical review of mercury fates and contamination in the Arctic tundra ecosystem is assessing the impacts and potential risks of Hg contamination on the health of Arctic people and the global northern environment by highlighting and “perspectiving” the various mercury processes and concentrations found in the Arctic tundra.     

杭州常用河道水生植物的种植要点初探

通过对杭州五大水系典型河道绿地水生植物的调查,分析了城市河道绿地水生植物在种植和养护管理中存在的问题,并结合水生植物自身的特点和河道环境,从种植时间、种植方法、种植密度及不同植物混植等方面,总结了杭州河道适用水生植物的种植要点,从而营造相对稳定的水生植物群落。     

Monitoring of Cryptosporidium and Giardia river contamination in Paris area

This study evaluates the protozoan contamination of river waters, which are used for drinking water in Paris and its surrounding area (about 615,000 m(3) per day in total, including 300,000 m(3) for Paris area). Twenty litre samples of Seine and Marne Rivers were collected over 30 months and analyzed for Cryptosporidium oocysts and Giardia cysts detection according to standard national or international methods. Cryptosporidium oocysts and Giardia cysts were found, respectively, in 45.7% and 93.8% of a total of 162 river samples, with occasional high concentration peaks. A significant seasonal pattern was observed, with positive samples for Cryptosporidium more frequent in autumn than spring, summer and winter, and positive samples for Giardia less frequent in summer. Counts of enterococci and rainfalls were significantly associated with Giardia concentration but not Cryptosporidium. Other faecal bacteria were not correlated with monitored protozoan. Marne seems to contribute mainly to the parasitic contamination observed in Seine. Based on seasonal pattern and rainfall correlation, we hypothesize that the origin of contamination is agricultural practices and possible dysfunction of sewage treatment plants during periods of heavy rainfalls. High concentrations of protozoa found at the entry of drinking water plants justify the use of efficient water treatment methods. Treatment performances must be regularly monitored to ensure efficient disinfection according to the French regulations.     

Distribution of mercury in six lake sediment cores across the UK

Six sediment cores, from Lochnagar, Loch Chon and Loch Grannoch in Scotland, Burnmoor Tarn in the English Lake District, Llyn Llagi in the Snowdonia region of Wales and Banbury Reservoir in London, were taken in order to study the distribution of Hg temporally and historically in lake sediments across the UK. These cores were dated using the spheroidal carbonaceous particle technique. The cores show that all sites across the UK have been contaminated by Hg. There is a rapid increase in Hg concentration during the last approximately 200 years at all rural sites. In the 95 year record from Banbury Reservoir in London the sediments show high Hg concentrations (380-840 ngg(-1)) throughout. Inter-site differences in Hg concentrations and profiles may be explained by impacts of afforestation, composition of the sediments and the provenance of the Hg including catchment in-wash influences. For example, catchment contributions result in a sharp peak (1606 ngg(-1)) in the Hg concentration profile in the core taken from Loch Chon in the Trossachs region of Scotland. Mercury fluxes were calculated for the sediment cores and show that over the last few decades these UK sites, except Lochnagar, would fall into the upper range for European rural areas.     

Temporal and spatial trends of mercury in fish collected in the English-Wabigoon river system in Ontario, Canada

The First Nations communities of Grassy Narrows and Wabaseemong (Ontario, Canada) have been impacted by mercury pollution since the 1960s. This study was implemented with the objective of providing these communities with information on current mercury concentrations in their catch, in order to make appropriate fish consumption choices. A total of 851 fish samples, including Walleye, Northern Pike, Large-mouth Bass, and Whitefish, were collected from thirteen lakes and rivers. Total mercury was measured and the relationship between fish length, mercury concentration, and lake of origin were assessed. It was found that fish from most of the lakes exhibit a positive relationship between length and mercury accumulation. Mercury concentrations in fish collected from Clay Lake, closest to the original source of contamination, are higher than those from other lakes. Mercury concentrations have declined over the last 25 years but the gradient of contamination was still observed. Results were communicated to the communities for public health purposes.     

Accumulation and transformation of atmospheric mercury in soil

Field investigation and simulating experiments were carried out for understanding the accumulation and transformation of mercury in soil in relation to the deposition of atmospheric mercury. A positive correlation between the atmospheric mercury concentration and the content of mercury in soil was observed in the field investigation, with the correlation coefficient being 0.741** (n=52). The mercury content in soil decreased with the increasing distance from the mercury emission source. Simulated experiment demonstrated that the higher the mercury content in air was, the higher was the amount of mercury accumulated in soil, which was in accordance with the results found from the field investigation. Transformation process occurred once mercury deposited into the soil. Analyses of soil samples exposed to air with mercury contents of 796.4+/-186.3 ng/m(3) for 2 months indicated that 24.58-26.86% of total mercury deposited into the soil existed in Hg(0) form, 0.10-0.12% in active form, 14.56-18.75% in HCl-dissoluble form, 0.86-5.84% in organic-bound form and 52.64-55.29% in residual form.     

Escherichia coli contamination of the river Thames in different seasons and weather conditions

Contamination of public water ways with sewage represents a serious environmental and health risk. We monitored pollution of the river Thames by enumerating the indicator organism Escherichia coli. Samples were taken from a site in central London near Waterloo Bridge in different seasons. E. coli were quantified using a membrane filtration method, and correlated with the tidal variations of the river and meteorological data on rainfall and temperature. More frequent and severe incidents of pollution occurred in the autumn. Heavy rainfall resulted in sharp peaks of E. coli contamination that implies a potential increase of numbers of pathogenic micro‐organisms. Sixty percent of all samples were found to be in excess of the accepted upper limit of pollution set by European Union (EU) legislation for bathing water. This study demonstrated that frequent sewage pollution of the Thames results in high numbers of E. coli and incidents of detectable levels of pathogenic bacteria demonstrating the need for regular monitoring of bacterial pollution.     

Genotoxicity in water and sediment extracts from the St Lawrence river system, using the SOS chromotest

Surface water and sediments from the St Lawrence River system (Québec region) were analysed for genotoxicity using the SOS Chromotest, as well as for their chemical concentrations of polycyclic aromatic hydrocarbons and heavy metals. Additionally, chlorobenzenes, polychlorinated biphenyls, organochlorinated pesticides, ammonia and nitrite concentrations in sediments were determined. Water and sediments sampled from twenty-five sites were initially partitioned into their aqueous and particulate phases by tangential flow filtration and centrifugation, respectively. Organic contaminants were extracted from the fractions with dichloromethane. For surface water, fifteen extracts of filtered water and seven of particulates, and for sediments one extract of pore water and three of particulates proved to be weakly genotoxic. All but one of the genotoxic responses observed in the surface water were obtained from samples taken from the highly industrial portion of the St Lawrence River system, with the strongest responses observed in Lake St Louis. Surface water genotoxicants partitioning favours the particulate fraction. Bottom particulates genotoxicity was 1000-fold weaker than suspended particulates, on a per unit weight basis. Additionally, whole sediments were extracted with a 10% dimethylsulfoxide-saline solution. The observed distributions of genotoxicity values did not correlate with observed concentrations of demonstrated SOS inducers, mutagens and/or carcinogens, nor with the presence of other toxic chemicals.     

Degradation of chlorophenols in soil, sediment and water at low temperature

Chlorophenol degradation was studied under aerobic conditions in soil, sediment and water. Ortho-chlorophenol, p-chlorophenol and 2,4-dichlorophenol were degraded by soil and sediment microorganisms at 0°C and 4°C. Metachlorophenol and pentachlorophenol were also degraded, but to a lesser extent. Stream-water microorganisms were only able to degrade 2,4-dichlorophenol at 20°C. None of the other chlorophenols examined were degraded by stream-water microorganisms at 0 or 20°C. The addition of some chlorophenols stimulated aerobic, and to a lesser extent, anaerobic microbial growth in sediment incubated at 0°C. A decrease in the concentration of some chlorophenols was noted in both sterile and non-sterile stream water at 0 and 20°C; which could not be explained by microbial contamination, photodecomposition or volatilization.     

Modelling of mercury transport and transformation processes in the Idrijca and Soca river system

In the town of Idrija, Slovenia, the world's second largest mercury mine was active for 500 years and about 37,000 tons of mercury has been lost in the environment. Mercury is still drained from soil, riverbed and floodplains and transported with the Idrijca and Soca Rivers to the Gulf of Trieste. A part of inorganic mercury is methylated either in the river system, or later in the coastal area, and, due to its bioaccumulation and biomagnification represents potential danger to human health. A 1-D aquatic model MeRiMod was used to simulate hydrodynamics and sediment transport in the river system from Idrija to the Soca River mouth. Transport of particle bound and dissolved mercury as well as potential net methylation of mercury in the river system was simulated. The simulation of an observed flood wave with 20-year recurrence period was performed in order to validate the model. Methylation was simulated at lower discharges, as higher methylation rates occur in such conditions. The measurement data and the MeRiMod model were also used to establish a historical mercury mass balance of the Idrijca and Soca Rivers catchment. Sediment core data from the Gulf of Trieste and the measured concentrations from floodplains were used to verify and calibrate the model. Simulations of different high discharges were performed as most of the transport of particulate mercury occurs within flood wave conditions. Compared to the measurements, the results of the model showed an agreement within an order of magnitude, for the transport of total mercury mostly within a factor of 4, and for the methylation within a factor of 5. However, proper trends of the phenomena were obtained by simulations. The combination of modelling and measurements has resulted in some interesting conclusions about the phenomenon of the transport and transformations of mercury in the observed river system.